A pilot study to establish non-invasive biomarkers for higher-grade meningioma

Abstract

INTRODUCTION: Meningioma brain tumours are the most common primary tumour in adults. Despite surgery and/or radiation therapy, men-ingioma may recur. The 5-year recurrence rate in benign meningioma is estimated in about 10% while much greater in atypical and malignant tumours. MicroRNAs (miRNAs) represent a large class of small RNAs driving regulation of gene expression and playing a role in tumour progression and therefore proposed as diagnostic tools. Moreover, miRNAs can be released from tumour cells into the blood stream via exosomes, showing potential to be used as liquid biopsies. METHODS: Identifcation of novel circulating biomarkers was conducted by performing an unbiased Cancer MicroRNA qPCR Array, followed by bioinformatics analysis. In parallel, we conducted a biased in silico analysis of the miRNAs targeting Cyclin D1 and E1, recently proposed as immunohistochemical meningioma biomarkers. Validation studies performed using TaqMan® reagents. RESULTS: Stringent unbiased (p<0.01) miRNA profling followed by validation in ex vivo samples revealed that the miR-9-1 is upregulated in higher-grade meningioma tissues and serum exosomes, controlled by the EGFR/AP-1 axis and correlated with lower levels of E-Cadherin, a proposed biomarker for malignant meningioma. On the contrary, biased analysis, followed by validation in vitro and ex vivo, showed that the miR-497~195 cluster is downregulated in higher-grade meningioma tissues and serum exosomes, correlating with the overexpression of GATA-4, a novel meningioma tissue biomarker. CONCLUSION: Our data demonstrated that both miR-497~195 and miR-9-1 show potential to become promising non-invasive biomarkers for highergrade meningioma, refecting their expression status in tissues. (DB and CN contributed equally).